In: Mechanical Engineering
Two parts of a machine are held together by eight equally-spaced M6x1.0 grade 5.8 bolts that are unifomly tightened to provide a total inital clamping force of 44 kN. Each bolt has a proof stress of 380 MPa, and a threaded area of 20.1 mm^2. The elasticities are such that the member stiffness is four times as high as the member stiffness.
b) You have determined that assembly procedure can reliably set the initial clamping force to within plus or minus 20% of the nominal value. What do you recommend as a safe working load if you require a factor of safety of 2.5 against any failures?